This invention relates generally to movement of valve stoppers, and more particularly concerns the operation of safety valves used in well tubing strings and kellycocks used in drill pipe strings.
It is extremely important that safety valves and kellycocks be operational at all times. Safety valves and kellycocks are typically manually operated by means of wrenches at the string exterior in order to close off flow in the string as during a possible well blowout. It is particularly important that when the valve stopper is open, an unrestricted bore is achieved to avoid turbulence, cavitation and pressure losses. It is equally as important that the valve stopper be properly aligned when closed to obtain a leak proof seal. Binding or misalignment of such kellycocks and safety valves, or difficulty with their operation, must be avoided; however, in the past the construction of the valve stopper rotating apparatus did not always assure trouble-free operation or proper alignment at all times, whereby serious problems could arise.